The genetic contribution to a number of neurological disorders is thought to be complex in nature, disease risk being driven by a combination of risk alleles commonly present in the human genome. Recently the completion of stages I and II of the international Haplotype Map project and the availability of high-plex SNP assays has made genome wide assay of common genetic variability a realistic endeavor. We have applied genome wide association analysis using 500,000SNPs to a Parkinsons disease cohort from the NIH funded neurogenetics repository. We have combined the data from this work with collaborators from Germany, the US, the UK and Japan. This work has lead to the identification of common variability in SNCA and MAPT as unequivocal risk factors for Parkinson's disease. Further this work has identified a novel locus on chromosome 1 as a risk factor for PD. We have now extended this work and combined results with other large genotyping projects in PD and related diseases to identify additional risk loci for this disease, identifying an additional 7-10 risk loci for Parkinson's disease. We plan to follow this with replication genotyping and resequencing to nominate common and rare risk variants in these diseases.